Human embryonic stem cell (hESC) research depends upon the ability of these cells to remain pluripotent and genetically stable in culture as a self-renewing population. This stability and functionality must also be maintained after directed differentiation into multiple cellular lineages. Current culture conditions for hESCs are sub-optimal and this can lead to acquisition of chromosome abnormalities, sporadic differentiation, genomic alterations and decreased cell viability. Before hESCs will be useful clinically, standard protocols must be developed to ensure accurate and repeatable methods for hESC maintenance, culture and differentiation. Although most of the NIH approved lines share common characteristics, a wide range of culture conditions have been published, which makes comparisons of different methods difficult. The hESC Core Facility (Core B) is developing standardized hESC culture methods with the goal of assisting researchers in this program project with hESC culture techniques. The core will provide expertise in growing, splitting, monitoring and determining valid protocols for hESC culture methods. In addition, the core will develop crucial reagents for each of the projects, as detailed in Projects 1-3. Core B will provide a means for project integration and comparison, and also train investigators as new technology develops. Core B will provide novel biosynthetic culture surfaces to optimize hESC growth in both undifferentiated and differentiated states. Thus, Core B will provide both service and experimental activities for the benefit of the program project. The Specific Aims of the Stem Cell Core are: Specific Aim 1. To culture, bank and distribute hESCs for the program project Specific Aim 2. Monitor differences over prolonged culture conditions with multiple hESC cell lines Specific Aim 3. Optimize growth conditions with multiple hESC lines as needed for each project Specific Aim 4. Provide hESCs with stable vector integration and lysates as needed per project Specific Aim 5. Develop new directions in synthetic materials and architectures Specific Aim 6. Integrate projects and facilitate transfer of information between each project